This invention relates generally to extracts of Mad-dog skullcap and to methods for obtaining such extracts.
Mad-dog skullcap (Scutellaria lateriflora L., Lamiaceae) is a perennial herb indigenous to North America, growing in wet places from Canada to Florida and westward to British Columbia, Oregon and New Mexico. It derives its common name from the helmet-shaped upper lid of the seed pods. The aqueous extract of the flowering parts has been traditionally used by Native Americans as a nerve tonic and for its sedative and diuretic properties (Burlage H M, (1968) Index of the Plants in Texas with Reputed Medicinal and Poisonous Properties, Coll. Pharm. Univ. Texas, Austin; and Millspaugh C F, (1974) Scutellaria, in: American Medicinal Plants. Dover Publications, New York, pp. 469-472). Due to the lack of scientific studies on the plant, the use of skullcap has been very controversial.
Work on the chemistry of S. lateriflora has been performed only recently. Mono- and diterpenes (Yaghmai M S, (1988) Flav. Frag. J. 3: 27-31; and Bruno M, Cruciata M, Bondi M L, Piozzi F, De la Torre M C, Rodriguez B, Servettaz O, (1998) Phytochemistry 48: 687-691) have been reported as well as the flavonoids baicalin, baicalein, ikonnikoside I, scutellarin, lateriflorin (5,6,7-trihydroxy-2′-methoxyflavone-7-O-glucuronide), lateriflorein (5,6,7-trihydroxy-2′-methoxyflavone), oroxylin A-7-O-glucuronide, oroxylin A, wogonoside and wogonin (Gafner S, Kelly L, Bergeron C, Gauthier R and Angerhofer C K, in: Abstracts of plenary lectures and posters, 44nd Annual Meeting of the American Society of Pharmacognosy (ASP), Chappell Hill, 2003: poster P228). Several of these flavones, isolated from the Baikal skullcap (Scutellaria baicalensis) have been evaluated for their ability to bind to the benzodiazepine site of the GABAA receptor. Baicalein and baicalin are weak ligands of this receptor, but wogonin and oroxylin A showed a strong affinity in these in vitro assays. (Liao J F, Wang H H, Chen M C, Chen C C and Chen C F, (1998) Planta Med. 64: 571-572; Hui K M, Wang X H and Xue H, (2000) Planta Med. 66: 91-93; and Wang H Y, Hui K M, Chen Y, Xu S, Wong J T F and Xue H). In another in vitro assay, several flavonoids from Scutellaria lateriflora have been able to bind to the 5-HT7 receptor (Gafner S, Bergeron C, Batcha L L, Reich J, Arnason J T, Burdette J E, Pezzuto J M and Angerhofer C K, (2003) J. Nat. Prod. 66:535-537).
Accordingly, it is desirable to develop useful extracts of Mad-dog skullcap and effective methods for obtaining such extracts.